Positive clutch with helicoidal tooth surfaces of varying lead



Oct. 6, '1953 POSITIVE CLUTCH WITH E WILDHABER HELICOI RYING LE TOOTH SURFACES OF VA Original Filed Jan. 4, 1943 2 Sheets-Sheet l Zhwentor ERNES r I W/LDHH BER Oct. 6, 1953 wlLDHABER 2,654,456

POSITI VE CLUTCH WITH HELICOIDAL TOOTH SURFACES OF VARYING LEAD Original Filed Jan. 4, 1943 2 Sheets-Sheet 2 lnnentor ERNES T WILDHHBER W aflorneu Patented (Jet. 6,

um're o STATES omcs of N ew' York- Originalapplicatio r January 4; 1943; Serial No; 17 1,Z33'. :.pivided and this application April 20, 19 18, Serial N0. 22,209

Claims (01. 192*108) The present invention relates to toothed face clutches; In particular; the invention relates to" the structure and production of clash-type face Clutches, that is, clutches whose members are" adapted to be engaged While the" driver; at mast, is" rotating. The present application is a divie sion of my cope'nding' application, Serial No. 471,233, filed January 4,1943, nowU. S. Patent" No; 2,443,089, granted June 8', I948, and covers" specifically the novel clutch of theinvention.

Since the teeth and tooth spaces ofth'etwo engagin members of a'clas'h-type clutch are not always in' exact registerwhen' the clutch members are moved into engagement, the teeth of such clutch members are chamfered along their top edges to facilitate engagement. Atthe beginning of engagement of such clutch members, the loads are high, shock loads; and it isimportant, therefore, that the chamfered portions of the teeth, as well as the main portions of the teeth; be able to stand and carry heavy loads;

A primary object of the present invention is to provide a toothedfacec'lutch which has chamfe'r surfaces correctly formed to carry'heavy'clashing loads. To this end, it is oneaim' of the inven'-' tion to provide ato'othed' face clutch whose meme ber have the chamfered portions of their teeth so shaped that they will contact midwavof the length of the chamfered' portionsand', if desired, along thewhole length thereof in all positions" of partial engagement of the clutch members as the" clutch members move into full engagement.' 4

Another object of the invention is-to providea toothed face clutch of the clash type'whose-mem'-' bers have chamfered surfaces generated to be conjugate to one another, that is, to have proper paired relationship to one'another.

Other objects of the invention willbe apparent hereinaiter'from the specification and from" the recital of the appended claims.

fered portions, that is; side tooth surfaces" and chamfered portions that are curved fromoneen'd" of each tooth to the other. The side tooth sur: faces of each clutch member are surfaces'of revolution, while their chamfe'r surfacesai'egenerat'ed surfaces, usually helicoidal' surfaces. Thete'rm" helicoidal surface, as used'in'the prescntspeci fication and claims, isemployed" in' a broad sense to describe'a surfaceofsuch a'smay be produced by a rotating cutting edgewhich'moves' along'anuj aboutan' axis and radially" of that" axis; usuany with avaryingratio of angular motion about said axis to axial motion along the axis, the axis, in the instant case being the work axis, and the term helic'oidal motion" is used; in a broad sense to describe a motion along and about and radially of an axis flhe axis referred; to coincides with the clutch axis. when the ratio of angular to axial movement varies, then the surface produced has, e ei e m ec Several difie'r'entembodi-mentsof the invention are illustrated in the accompanying drawings, in which: 7 r I Fig.1 is a part sectional, part plan View of one member of a clutch pair made according to one embodiment of this-invention, and illustrat ing diagrammatically one method of cutting this clutch member V H I V v Fig. 2 isa'part elevational, part axial sectional view, further illustrating. the structure of the clutch-member and the process of producing the same;

Fig. 3', is a diagrammaticview showing a tooth of the clutch member inanormal section midway of its length and further illustrating; the tooth structure and the method of chamfering a side o'fatooth;

.- i we 6 ar view m a i 2 and 3,. respectively, showing the construction of a clutch m emb'e'r which is; to mate with the clutch member of Figs. 1 to3 inclusive, and illustrating the method of producing this mating clutch member;

Figs. 7, 8 and- 9 are viewssimilar to Figs. 1-,

2 and arespecmveiy, and'illustr'ating the present preferred method 'of' producing one member of a clutch pair according to this invention, andFigs. 1'0 and 11 are viewssimil'ar' to Figs. 4 and 5, respectively, illustrating the present preferred method of producing the mating clutch member;-

Fig. 12 is 'a sectional view showing apair of' method or cnam' ferin the teethof this clutch member;

Fig.1'5jis. a'normal sectional view, midway of thefl'engthoi a tooth of a clutch member made according to a still further modification of themvenumrg' and" of the invention illustrated in Figs. 1 to 6 inclu-. sive. Here 23 and 2| denote, respectively, the two members of a clutch pair. The clutch members and 2| shown have fewer teeth than would ordinarily be employed, but such members have been shown because the principles underlying the present invention can be more clearly illustrated on the larger scale of the teeth shown.

Clutch member 20 has teeth .22 which extend generally radially of the clutch axis 23 and whose opposite sides 24 and are longitudinally convex, that is, convexly curved from one end of a tooth to the other. The mating clutch' member 2| has teeth 21 which extend generally radially of the clutch axis 23 and whose opposite sides 28 and 29 are longitudinally concave, that is, concavely curved from one end of a tooth to the other. The teeth 22 of clutch member 20 are chamfered along their top edges as denoted at and'3l. The teeth'2l of clutch member 2| are chamfered along their top edges on both sides as denoted at 32 and 33. portions 30 and 3| of the teeth of clutch member 23 are longitudinally convex, While the chamfered portions 32 and 33 of clutch member 2! are longitudinally concave.

The sides 24 and 25 of the teeth of clutch member 20 are of zero pressure angle and straight profile shape, having their profiles extending parallel to clutch axis 23. The sides 28 and 29 of clutch member 2| are also of zero pressure angle and straight profile shape, also having their profiles extending parallel to clutch axis 23. The sides 24 and 25 of clutch member 29 are convex cylindrical surfaces of revolution and the sides 28 and 29 of clutch member 2| are con cave cylindrical surfaces of revolution. The chamfer surfaces 30 and 3| of clutch member 29 are helicoidal surfaces of convex profile shape; and the chamfer surfaces 32 and 33 of clutch member 2| are also helicoidal surfaces of convex profile shape. Theteeth of both clutch members have well rounded fillets at their roots, as denoted at 36 and 31, respectively.

7 The nature of the helicoidal chamfered surfaces is illustrated in Figs. 16 and 1'7 which show a chamfered surface 3| of a tooth of clutch member 20. 221, p2, 1103 and m, respectively (Fig. 16), are the lines of intersection with the chamfered surface 3| of equi-spaced parallel planes I, II, III and IV, respectively (Fig. 17), which are perpendicular to the clutch axis 23. Curves p1, 192, p3 and 124 are radial of the clutch axis 23 at points in their lengths which are equi-distant from the clutch axis 23, as indicated in the cases of mean points P1 and P4 in Fig. 16. Lines 34 and 35, tangent to curves in and 114 at the points P1,]P4, respectively, intersect in the clutch axi 23. Surface 3| is a surface twisted three-dimensionally. It is a helicoidal surface of varying lead.

By varying lead is meant that the inclination of the chamfer, considered in profile, as in Fig. 1'7, changes from top to bottom. At the top of its profile the chamfer is inclined at a much larger angle to clutch axis 23 than at the bottom of its profile. In fact at the bottom of its profile the chamfer merges into the tooth side surface 25 and hence at this point is parallel to, or has The chamfered' 4 zero inclination to, the axis 23. Considered from a different viewpoint, the varying lead helicoidal shape of the chamfers means that as the mating clutch members are rotated about axis 23 and simultaneously moved. axially therealong, with their chamfers in contact, so as to bring the tooth side surfaces into mesh, the rate of the axial motion varies (increases) in relation to the rate of the rotational motion. After the tooth side surfaces have thus been brought into engagement there is no further rotation, and the clutch members move only axially until their teeth come into 'full depth mesh.

For cutting-and chamfering the teeth of clutch member 20, a face mill cutter 40 may be used.

4 This cutter,- which is shown more or less diagrammatically, has a plurality of blades 4| which A are arranged circularly about its axis 42 and which havecutting portions that project beyond one side face of the cutter in the general direction of the axis of the cutter. Each blade 4| has a straight side cutting edge 43, a convex chamfering edge 44, and a tip cutting edge 45. It may also have an outside cutting edge 46. Chamfering edge 44, which is preferably of circular arcuate shape, connects the side-cutting edge 43 with the tip-cutting edge 45. The insides of the blades are the finishing portions and the outsides are just to remove stock. The outside edges therefore may be, and usually are, placed on separate blades which may alternate with the blades having the inside cutting edges.

The cutter 4il'is positioned with its axis 42 parallel to the axis 23 of the clutch so that it will operate in two spaced tooth zones of the work simultaneously.

One of the blades 4| of the cutter is shown in full lines in Fig. 3 at the beginning of the cut on the chamfered portion 33a of a tooth 22a of the work. As the cutter revolves on its axis, a relative helicoidal movement is produced between cutter and work until the cutter reaches the dotted line position denoted at 4|. Then the relative helicoidal motion'between the rotating cutter and the work ceases but the depthwise feed component is continued until the cutter reaches full depth position. This position is shown in Figs. 1 and 2. During the depthwise feed movement, opposite sides of two spaced teeth of the work, such as the sides 24a and 25b of the teeth 22a and 22b, respectively, of the clutch member, are cut as parts of a common cylindrical surface whose axis coincides with the axis 42 of the cutter. In full depth position, these sides and the root portions l6 of the teeth are finished. Then the depthwise feed movement is reversed, causing withdrawal of the cutter from full depth position. After the cutter has been partially withdrawn and the cutter has reached a position with respect to the side 25b of tooth 222) corresponding to that shown in dotted lines at 4| in Fig. 3, the helicoidal motion is started again, by adding to the feed component the turning component, so that the chamfer surface 3| 1) may be produced on the tooth 22b in the'further withdrawal movement- When the cutter has cleared the work, the blank is indexed, and the cycle starts anew.

In order that the chamfer surfaces of mating clutch members be able to carry heavy loads, the first and main requirement is that the mating chamfered portions of the engaging clutch members be so shaped that the chamfered portions will contact at mean points in the length of said chamfered portions. This may be fulfilled when the. mating chamfered portions of the teeth of 5 the engaging clutch members have the same lengthwise direction at mean points in a plane perpendicular to the clutch axis, for instance, a radial direction. Secondly; it is desirable that these conditionsof contact be fulfilled not only at a. mean point in the length of the chamfered part of a tooth, but at other points in the considered plane as well. Thirdly, it. is desirable that the contact between the chamfered portions of the engaging clutch members extend lengthwise of the teeth for a suflicient distance to carry the loads, but preferably not to the ends of the teeth.

In the full line position of the. blade 41' in Fig. 3, the convex cutting edge 44 of the blade contacts with the chamfered' portion 30a of the tooth 22a at point 50. This point has a distance 1' measured radially of the; cutter from cutting edge 43 and a radial distance 1. from the side 24a of the tooth. The. points in. the cutting edges of the tool, which are adapted to, make contact at point 50,. are all located in a circle 52' which is shown in dotted lines. in Fig. 1. The radius of this circle exceeds by the distance r'the radius of the circle 53, which contains the points in the side cutting edges 43', which are adapted to cut the tooth side 24a. The circle 53 in the full depth position shown in Fig. l is tangent at mean point 54 to a line 55' radial of the clutch axis 23.

It is obvious, that in the full depth position shown in Fig. l the circle 52 is not radial of the clutch axis at mean clutch. radius 23-54; However, our object of obtaining chamfer surfaces on the clutch member 20, which will be radial of the clutch axis at mean points in their lengths, is attained when the circles, like circle 52; containing points of contact between the cutter and a chamfer surface are radial of the clutch axis in their respective positions of contact during partial depthwise engagement of the cutter and clutch member. This requisite is fulfilled for the considered point 51! when the cutter is displaced along its radius 54-42 a distance 1* so that its axis moves from position 42 to position 4211 and the circle 52'. will pass, through point-.54 and be tangent to clutch radius 2,354, and when the cutter is further moved relatively about the clutch axis 23 through an angle 54-23-53, until the circle 52 passes through a considered point of'contact' 50 on the chamfered surface 30a of the clutch tooth. In this last described turning motion about the clutch axis, the cutter center moves to position 42, angle 42'-23,-42a being equal to angle 54-23-50. The position 42' of the cutter axis is coordinatedwith the depthfeed position of the cutter as will be obvious, for the position 42 of the cutter axiscorresponds'to the positionwhere the cutter makes contact withthe chamfer surface 30a in point 50 of that surface.

Other angular positions of the cutter axis for other depth-feedpositionsof'the cutter andfor other points of contact between the cutter and the chamfer surface to be produced can be obtained in the same way as described for determine ing the position-42", The various relative. positions ofthe cutter axis for different points of contact between the cutter and, the chamfer surface being produced constitute a curve 42-42 shown indotted lines in Fig. 1.

In the production of the chamfer, surface 30a, then, the out starts-in-the'position'shownin full lines in Fig. 3, with thecutter axis at position 42' (Fig. 1'). As the in-feed proceeds; a-relative generating movement is'effected betweenthe cutter and the work so that the cutter-axis moves relatively toward position- "which is-attained when the in-feed has proceeded far' enough for the cutter to have attained the dotted line position 4| shown in Fig, 3. From this point, the movement of translation is stopped but the in-feed continues, preferably at: a uniform rate until depth position is nearly reached. Then the infeed slows down and when full depth position is attained, which is the position where the sides 24a and 2517 are completed, it is reversed. When the cutter has againreached the position shown at 4| on the out-feed, the generating movement is again started in the same direction as before and the generation of the chamfer surface 31b of tooth 22b starts; As the out-feed continues, preferably at a uniform rate, the cutter axis moves along a curve 42-42 (Fig. 1), until the chamfer surface 3l'b has been completed. The curve 42-42 may be determined for the chamfer surface 311) in thesame manner as the curve 42-42 was determined for the chamfer surface 36a. The curve 42-42 will be a curve symmetrical to the curve 42-42 with respect to the axial plane 23-42, if the chamfered surfaces on opposite sides of the teeth of the clutch member have the same profile shape;

The described relative movement of the cutter axis from position 42' toposition 42 and then to position 42 may be resolved into a turning motion of the work on its axis23 and a radial displacement of thecutter axis'in the plane 23-42. Thus position 42" may be arrived at by turning the work through anangle 42-23-42", and by moving the cutter axis outwardly from position 42 to position 42?). Thislatter point lies on circle 51 which passes through point- 42". Thus the motions required forgeneration of the chamfer surfaces may be resolved into three coordinated relative motions. These are the depthwise feed movement inthe directionof the clutch axis; relative turning motion about the clutch axis, and a rectilinear motion in the plane containing the clutch and cutter axes. The depth feed movement is preferably at a uniform rate. The turning motion will depend'uponthe mechanism employed to rotate-theblank. The rectilinear motion will depend onthe-turning motion.

A Geneva motion may be conveniently employed for the turning motion, since it can-beused not only for rotation of the work intermittently for chamferingbut'alsofor rotation of the work intermittently for indexing. The turning motion determines the nature of the profileofthe chainfer surface, and determines, also, the linear feed motion required, since this motion should be of the same nature as the turning motion. Considerable latitude prevails, therefore, in selecting-the profile shape of thechamfer surface since this shape can be chosen with reference to the indexing motion available.

The method ofgenerating theclutch member 2|, which is to mate with clutch member- 26, is shown in Figs. 4, 5. and' 6. A face mill cutter 60 is used which hasblades-fil arranged circularly about its axis 62. These blades have outside cutting edges 63of straight; profile. andzerdpressure angleand convex-.chamfering edges 64. The stocking-out edges 66, which serve simply to remove stock, may be on the; same blades as the outside edges 63, as shown, or on separate blades.

The cutter 60 is so positioned with reference to the work that it will operate simultaneously in two spaced tooth zones of the work and its axis is placed parallel to the axis 23 of' the work so as to out side' tooth surfaces on the work ofzero pressure angle. The diameter of the cutter is .selected so that a tangent to a side-tooth surface produced, as, for instance, the tangent 65 to the side tooth surface 29a of tooth 21a at mean point 64 will be radial of the clutch axis 23. Then the mating side tooth surfaces of the two clutch members 20 and 2| will have the same length- Wise direction and proper contact. The motions required to produce chamfer surfaces on clutch member 2|, which will have the same lengthwise direction (radial) at mean points as the chamfer surfaces of clutch member 20, can be determined in the same way as already described for clutch member 20.

A blade 61 of the cutter is shown in Fig. 6 in position at the beginning of production of the chamfer surface 33a. 10 is a point of contact between the convex cutting edge G l of the blade and the convex chamfer surface 33a to be produced. The point of contact 10 lies inside of the side cutting edge 63 of the blade at the radial distance 'r' and outside of the straight profile 29 of the tooth at the radial distance t. The points in the chamfering edges 64 of the cutter, which are adapted to cut at point 10 of the chamfer surface, all lie on a circle 12 (Fig. 4). In Figs. 4 and 5, the cutter is at full depth position and points in the side cutting edges 63 of the blades are finishing the sides 29a and 28b of the spaced teeth 27a and 211), respectively, of the work. 7 To determine the position which the cutter should occupy in order to have the mean point 70 radial of the clutch axis when the chamfering edge 64 and the chamfer surface 33a contact at point 10, the axis of the cutter is displaced from position 62 in Fig. 4 first to a position 62a. along line 64-62 until circle 12is tangent to a clutch radius 23-54 at point 64, and then the cutter is moved about the clutch axis 23 through an angle 64-23-10 to bring the circle 12 into contact with the chamfer surface 330. at point 10. The distance 62-6211. is equal to 1'' that is, to the distance between circles 12 and 73.

When the circle 12 of the cutting points is tangent to the radial line 23-70, the axis of the cutter will be at point 62. This is the position of the axis of the cutter at the start of the out, then, on the chamfer surface 3312.. In producing the chamfer surface 330., then, the cutter is 1'0- tated on its axis While a relative movement is produced between the cutter and the work in such way as to move the cutter axis from position 62' to position 62 and in time therewith a relative depthwise feed movement is produced between the cutter and the work.

When the cutter has, been fed relative to the blank to a position where the cutting edge 64 of the cutter makes contact at point 1| (Fig. 6), the chamfer surface 33a will have been completed. The relative generating motion between cutter and work is then stopped, but the depthwise feed movement is continued to produce the opposite sides 29a and 28b of the spaced teeth 32a. and 321). Then the withdrawal motion of the cutter starts. When the cutter has been artially withdrawn to a point where the convex cutting edge 64 of the cutter is making contact with the tooth side 28b at a point in the height of that tooth side corresponding to point H, the generating motion is started again, the turning motion about the clutch axis being in the same direction as during chamfering of surface 33a. Then, as the generating motion continues in time with the out-feed movement, the convex cutting edges 64 of the cutter will generate the chamfer surface *8 3212. In this movement, the axis ofthe cutter will move from position I52 to position 62".

The relative motion of cutter and work in generation of the chamfer surfaces of clutch member 2| may be split up, as in the case of the chamfer surfaces of clutch member 20, into a radial displacement of the cutter axis in the axial plane 23-62, into a turning motion about the clutch axis 23 and into depthwise feed in th direction of the clutch axis. Thus the cutter axis, in effect, is gradually moved to a maximum center distance 23-62 at which the opposite sides of spaced teeth of the clutch are cut, and then back again. This is the reverse of the motion of the cutter in the cutting of the mating clutch member 20, for in the cutting of member 20, the cutter is gradually moved to a minimum center distance 23-42 at which the sides are cut, and then back again.

In the above described embodiment of the invention, the mating chamfer surfaces as well as the mating sides of the teeth of the clutch members all extend radially of the clutch axis 23 at mean points in their lengths, that is, they are all tangent to lines which extend radially of the clutch axis at a given radial distance, namely, distance 23-54 in the case of clutch member 20 and distance 23-64 in the case of clutch member 2|. The distances 23-54 and 23-64 are equal. It is not necessary, however, that the mating sides and mating chamfered surfaces extend radially of the clutch axis. The tangents to these surfaces may be non-radial of the clutch axis providing that these tangents all have the same distance from the clutch axis and all lie on the same side of the clutch axis when the clutch members are in engagement. When looking at the fronts of the two clutch members, this means that the tangents should be offset the same distance at opposite sides of the clutch axis.

In a still broader aspect, the tangents may have varying distances from the clutch axis providing that mating points of the two clutch members have tangents at the same distance from the clutch axis and offset at the same side of the clutch axis when the clutch members are in engagement. Mating points are simply points where the surfaces of the clutch teeth have the same pressure angle, for instance points 50 and 10.

In the above described embodiment of the invention, the chamfer surfaces join the straight side surfaces of the teeth of the clutch members smoothly without break. When contact between the cutter and the work is made. for instance, at the point of juncture 5! (Fig. 3) between the chamfer surface 30a and the side tooth surface 24a, the cutter axis is in the same position 42 as when cutting the tooth sides.

The cutters i0 and Bil have the disadvantage that their side-cutting edges are of zero pressure angle and must be radially as well as axially relieved. Hence, when the blades are sharpened, the blades must be adjusted radially in the cutters in order to compensate for the change in radial position of the cutting edges. This disadvantage can be overcome, for I have found a way of using cutters having side cutting edges of positive pressure angle which are axially relieved. Preferably, then, face clutch members are out according to this invention with cutters of the type shown in Figs. '7 to 11 inclusive. These figures illustrate the production of two mating clutch members and 8|.

. Clutch member 80 has teeth 82 whose sides 84 and 85 are of longitudinally convex shape and whose chamfer surfaces 90 and 9I are also of Iongitudinally convex shape. The tooth sides 84 and 85 are convex cylindrical or conical surfaces of straight profile and zero pressure angle and the chamfer portions are helicoidal surfaces of convex profile and varying lead. Member 8| has teeth 81 whose sides 88 and 89 are longitudinally concave and whose chamfer surfaces 92 and 93 are also longitudinally concave. The tooth sides 88 and 89 are concave cylindrical or conical surfaces of straight profile and zero pressure angle. The chamfer surfaces 92 and 93 are ordinarily helicoidal surfaces of convex profile.

The teeth of clutch member 80 are cut with a face mill cutter I which finishes with its inside cutting blades IN. The blades IOI are arranged circularly about the axis I02 of the cutter to extend in the direction of said axis, and they have cutting profiles consisting of a straight side cutting edge I03 and a convex chamfering edge I04. The side cutting edges I83 are inclined at a positive pressure angle to the cutter axis I02 and so are all the elements of the chamfering edges I04. This means that the cutter I00 can be relieved axially and will hold its diameter and shape after sharpening. It means, also, that the cutting tool may readily be made in the form of an annular grinding wheel if desired.

The cutter I00 is tilted outwardly with reference to the clutch blank so that the conical surface described by its straight side-cutting edges I03 will be of zero pressure angle at mean points 98 and 99 in the two tooth zones in which the cutter operates. The cutter axis I02 will then intersect the clutch axis 83 when extended.

The position of the cutter relative to the blank and the relative movements of cutter and blank can be determined according to the same principles as described with reference to Figs. 1 to 6 inclusive. The profile of a cutter blade I M is shown in full lines in Fig. 9 at the beginning of the cut when the cutting edge I04 is in contact with the chamfered portion 90a of a tooth 82a of the work at point IIO. Again in the generation of the chamfer surfaces of the clutch memher, the feed can be resolved into three motions, namely, motion along and about the clutch axis 83 and a lateral feed motion in the plane of the cutter and clutch axes. If the cut starts, as shown in Fig. 9, at the top of the chamfered surface 90a, the work 80 turns in a clockwise direction about its axis 83 at a gradually decreasing rate as the depth feed proceeds inwardly. -At the same time, the cutter is moved radially toward the clutch axis 83 also at a gradually decreasing rate. In the turning and radial movements, a point of the cutter axis moves from I05 to I05. When the central position I05 is reached and the cutter blade has attained the dotted line position I03 of Fig. 9 the chamfer is completed. At the dotted line position I03 (Fig. 9) contact between the chamfering edge I04 of the cutter and the chamfer surface 90a of the clutch tooth is at point I I I. Then the turning motion of the work on its axis comes to a stop and the work is held stationary on its axis while the depthwise feed movement continues until the cutter has reached full depth position. During this depthwise feed movement to full depth position, the tooth sides 84a and 85b of spaced teeth of the work are finished. Then the depthwise feed movement is reversed and the cutter is withdrawn outwardly. When the cutter has been withdrawn to a position corresponding to 11 9 S otted line position shown at. I03 inFig. 9, the work resumes its turning motion in the clockwise direction but at a gradually increasing rate. At the same time, and also at a gradually increasing rate, the cutter axis is moved laterally away from the work axis 83 so that point I05 in the cutter axis will move to position I05. The chamfer of surface 9Ib is completed when the cutter has returned to a position corresponding to that shown in full lines in Fig. 9. When the cutter is clear of the work, the work is indexed, and then the cutting cycle begins anew.

Fig. 9 shows the path II2 of movement of the center II3 of convex cutting edge I04 during chamfering and cutting of the opposite sides of spaced teeth of the work. The chamfer surface 90:]. is generated during movement of the center of the cutting edge from I I3 to H3. The tooth sides 84a and 85b are finished when the center of the cutting edge I04 is in full depth position H3". The chamfering of surface 9Ib begins when the cutter has been withdrawn so that the center of its cutting edge I04 is again at H3, and this chamfer surface is completed when the center of the convex cutting edge I04 has reached position II3' on the left branch of path II2.

In Fig. 9, the path H2 is shown as curved instead of straight between points H3 and II 3". This is to obtain a partly sidewise approach to full depth position so that the straight tooth sides 84a and 85b may be formed with the straight side-cutting edges I83 of the cutter. The surfaces 84a and 85b lie, then, in the same conical surface, which is a counterpart of the conical cutting surface of the cutter. Movement of the cutter along the curved path II3I I3" has the added advantage that it prevents rubbing of the cutter on the finished side tooth surfaces of the work during the out-feed movement. In the out-feed movement the distance II3"I I3 may be traveled at an increased rate, if desired.

Fig. 9 illustrates an embodiment of the in- .vention where the chamfer profile a joins the side tooth surface 84a smoothly. The positions H3 and I I3" are then aligned depthwise with one another and are at the left of point I I3, that is, they have the same distance from side tooth surface 84a. If a slight angle is admitted at the exaggerated at I05a in Fig. 7.

It is also possible to envelop the straight profile 84a (Fig. 9) with the rounded cutting edge I04 by efiecting simple straight line axial feed movement between points 3' and H3". In this case the resultant tooth sides will be cylindrical surfaces terminating at inclined root lines I06 (Fig. 8). In this case the convex cutting edge I04 will be slightly prolonged, and straight cutting edge I03 will be given a slightly smaller positive pressure angle than shown. Path II3'-II3" (Fig. 9) will be straight then for the feed in one direction as for the in-feed, but may retain the shape shown for the feed in the opposite direction, as for the out-feed.

The clutch member 8|, which is to mate with I20 which match the direction of the inclinedv tooth bottoms I06 of clutch member 80. The tops I07 and I2! of they teeth of the two clutch members are preferably turned to follow the same general direction as their tooth bottoms.

In the embodiment illustrated, the outside diameter of cutter I20 is equal to the inside diameter of the cutter I00. In this case, the mating tooth sides of the two clutch members match each other along their whole length. It is possible, however, to reduce the lengthwise contact between the teeth of the clutch members and have that contact ease off at the tooth ends by reducing the diameter of the cutter I as compared with the diameter of the cutter I 20. Thus, the diameter of cutter I 00 may be reduced so that one less tooth is skipped between the two tooth zones in which the cutter operates.

In producing the clutch member 8|, opposide sides of spaced teeth of the clutch member and the chamfer surfaces at these sides of the teeth are again out in a single cycle of operation. This cycle again comprises depthwise in-feed followed by depthwise out-feed along the clutch axis 83 intermittent turning motion at a varying velocity in one direction about said axis, and intermittent radial feed motion of the cutter first in one direction and then in the other in a plane containing the cutter and clutch axes. The cutter is so moved in this last named movement that a point of its axis moves outwardly from I25 to I25 in the cutting of the chamfer surface 93a, and inwardly from position I25 to I25" during the chamfering of chamfer surface 92b. Here again, the cutter may be moved on a path similar to that shown in Fig. 9 so that it approaches the side tooth surfaces 89a and 881), which are to be cut, from a lateral direction and effects a smoother cut.

The invention is not limited to the production of clutch members having chamfer surfaces of convex profile shape, nor is it limited to the production of clutch members having chamfer surfaces which are helicoidal surfaces of varying lead. Fig. 14 illustrates diagrammatically a modification of the invention in which a clutch member is produced whose teeth I30 have chamfered surfaces I3I and I32 at opposite sides thereof that are straight profile. But one member of the clutch pair is shown in this figure. The chamfer surfaces of this member may be produced with a face mill cutter I35 that has inside cutting blades I36 which have inside edges I31 and rounded top edges I39. The inside edges I3? are of straight profile and they have sharp cutting points I33 formed at their junctures with the rounded convex top edges I39. At the intersection point I38, the rounded edge I39 has an inclination such that it includes a small angle with the chamfer surface being cut, as is clearly shown in the dotted position I36 of the blade. In this embodiment of the invention, no lateral feed of the cutter is required. The generating motion may consist simply of movement along and about the clutch axis. With this embodiment, however, more cuts, that is, more revolutions .of the cutter, are required to produce an,

acceptable finish. The chamfer surface produced may be a helicoid of constant lead and the movements about and along the clutch axis may therefore be at uniform rates.

The same tooth chamfer I3I of constant lead may also be produced by cutters, such as I00 and I20, having well rounded chamfering edges. In this case the uniform lead of the chamfers is produced with a constant radial position of the cutter, which is different from the radial position at which the straight side profiles are finished, as is clear from the foregoing description In Figs. 3, 6 and 9, chamfer surfaces are shown which have profiles that are convex and moderately curved at their middle portions and more curved at their junctures with the sides of the teeth. In Fig. 15, a further modification of the invention is illustrated. Here a clutch tooth I40 is shown which has chamfer surfaces MI and I42 that are of circular arcuate profile shape.

While the invention has been described in connection with clutch members having longitudinally curved teeth, it will be understood that in its broad aspects, it is also applicable to clutches having longitudinally straight teeth. Further, it will be understood that it is not limited in application to clutch members having side tooth surfaces of zero pressure angle but may be applied also to clutch members of positive pressure angle, although ordinarily its use is confined to clutch members of low pressure angle. Still further, it will be understood that while I have described the invention in connection with clutch pairs of which one member has side tooth surfaces that are logitudinally concave and the other member has side tooth surfaces that are longitudinally convex, both members may be made with longitudinally convex side tooth surfaces if quite restricted localization of tooth contact is desired.

It will be further understood that while a number of different embodiments of the invention have been described, the invention is capable of still further modification, and this application is intended to cover any variations, uses, or adaptations of the invention, following, in general, the principles of the invention and includig such departures from the present disclosure as come within known or customary prectice in the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth and as fall Within the scope of the invention or the limits of the appended claims.

Having thus described my invention, what I claim is:

1. A pair of toothed face clutch members whose teeth are chamfered along their top edges, the chamfered portions of the teeth of each member being helicoidal surfaces conjugate to the chamfered portions of the teeth of the other member.

2. A pair of toothed face clutch members whose teeth are chamfered along their top edges, the chamfered portions of the teeth of each member being helicoidal surfaces of varying lead conjugate to the chamfered portions of the teeth of the other member, and the mating chamfered portions of the two members having the same lengthwise direction at points of contact.

3. A pair of toothed face clutch members whose teeth are chamfered along their top edges, the chamfered portions of the teeth of each member being helicoidal surfaces of varying lead which are conjugate to the chamfered portions of the teeth of the other member and which are radial of the axis of the member at mean points in the chamfered surfaces.

4. A pair of toothed face clutch members whose teeth have longitudinally curved side surfaces and are chamfered along their top edges, the chamfered portions of the teeth of each member being helicoidal surfaces of convex profile shape conjugate to chamfered portions of the teeth of the other clutch member.

5. A pair of toothed face clutch members whose teeth have longitudinally curved side surfaces and are chamfered along their top edges, the chamfered portions of the teeth of each clutch member being helicoidal surfaces of varying lead and convex profile shape.

6. A pair of toothed face clutch members whose teeth are chamfered along their top edges, the chamfered surfaces of the teeth of both members being helicoidal surfaces, the chamfered surfaces of the teeth of one member being longitudinally convex in shape, and the chamfered surfaces of the teeth of the other member being longitudinally concave in shape.

7. A pair of toothed face clutch members whose teeth are chamfered along their top edges, the chamfered surfaces of the teeth of both members being helicoidal surfaces of convex profile, the chamfered surfaces of the teeth of one member being longitudinally convex in shape, and the chamfered surfaces of the teeth of the other member being longitudinally concave in shape.

8. A pair of toothed face clutch members, each of which has teeth that are longitudinally curved and that are chamfered along their top edges, the side surfaces of the teeth of each member being radial of the clutch axis at mean points in their lengths and the chamfered portions of the teeth of each member being also radial of the clutch axis at mean points in their lengths, the chamfered surfaces of each member being helicoidal surfaces.

9. A pair of toothed face clutch members whose teeth are chamfered along their top edges, the

chamfered portions of the teeth of each member being helicoidal surfaces, opposite sides of spaced teeth of each member being parts of a common surface of revolution, mating sides of the teeth of the two members having the same lengthwise direction at points of contact, and the mating chamfered surfaces of the two members having the same lengthwise direction at points of contact.

10. A pair of toothed face clutch members whose teeth are chamfered along their top edges, the sides and chamfered portions of the teeth of one member being longitudinally convex in shape and the sides and chamfered portions of the teeth of the other member being longitudinally concave in shape, opposite sides of spaced teeth of each member being parts of a common surface of revolution, and the chamfered portions at opposite sides of the teeth of each member being in the form of generated helicoidal surfaces of varying lead conjugate to the chamfered surfaces of the other member.

11. A pair of toothed face clutch members whose teeth are chamfered along their top edges, the sides and chamfered portions of the teeth of one member being longitudinally convex in shape and the sides and chamfered portions of the teeth of the other member being longitudinally concave in shape, opposite sides of spaced teeth of each member being of straight profile and extending at points intermediate their ends in the direction of the axis of said mem er and being parts of a common conical surface, and the chamfered portions at opposite sides of the teeth of each member being of convex profile shape and having the shape of generated helicoidal surfaces of varying lead conjugate to the chamfered surfaces of the mate member.

12. A pair of toothed face clutch members whose teeth have longitudinally curved sides and are chamfered along their top edges, the chamfers of each member being helicoidal surfaces conjugate to the chamfers of the other member, and mating chamfers having the same directions, both profilewise and lengthwise, at mean points along the length thereof, whereby they may contact at such mean points.

13. A pair of toothed face clutch members whose teeth are chamfered along their top edges, the chamfers of each member being helicoidal surfaces conjugate to the chamfers of the other member, and mating chamfers having the same direction, relative to the common axis of the two members, in planes perpendicular to said axis through corresponding mean points along the length of the mating chamfers at which their pressure angles are equal.

14. A pair of toothed face clutch members whose teeth are chamfered along their top edges, opposite sides of spaced teeth of each member being parts of a common surface of revolution, the chamfers of both members being helicoidal surfaces, and mating chamfers being tangent to each other at mean points along the length thereof in the various relative positions of the members in which the mating chamfers contact.

ERNEST WILDHABER.

References Cited in the file of. this patent UNITED STATES PATENTS Number Name Date 2,384,582 Wildhaber Sept. 11, 1945 2,384,583 Wildhaber Sept. 11, 1945 2,384,584 Wildhaber Sept. 11, 1945 2,443,089 Wildhaber June 8, 1948 

